Use of glycine-N,N-diacetic acid derivatives as biodegradable complexing agents for alkaline earth metal ions and heavy metal ions and process for the preparation thereof

ABSTRACT

Disclosed is the use of glycine-N,N-diacetic acid derivatives as their alkali metal, alkaline earth metal, ammonium and substituted ammonium salts as complexing agents for alkaline earth and heavy metal ions, except with α-alanine-N,N-diacetic acid, as textile detergent builders in powdered detergent formulations and as calcium sequestering agents in oral hygiene products.

This application is a 371 of PCT/EP94/01838 filed Jun. 6, 1994.

The present invention relates to the use of glycine-N,N-diacetic acidderivatives and their alkali metal, alkaline earth metal, ammonium andsubstituted ammonium salts as complexing agents for alkaline earth metalions and heavy metal ions with the exception of α-alanine-N,N-diaceticacid as textile detergent builders in powder detergent formulations andas calcium sequestrants in oral hygiene products.

The present invention furthermore relates to a process for preparingglycine-N,N-diacetic acid derivatives and to intermediates arising inthis process.

Since some of the glycine-N,N-diacetic acid derivatives represent novelsubstances, the invention also relates to these novel substances.

Japanese Published Specifications 80/157 695 (1) and 80/160 099 (2),quoted in Chem. Abstr. 95 (1981) 9123 m and 9124 n, respectively,disclose the use of alanine-N,N-diacetic acid in the form of the sodiumsalt as builder in textile detergents formulated in powder form, with anenhancement of the wash efficiency being observed in particular forcotton textiles.

EP-A 089 136 (3) relates to oral hygiene products which contain ascalcium sequestrant inter alia α-alanine-N,N-diacetic acid. These areused to control the amount of calcium fluoride supplied to the dentalenamel to protect from caries.

Complexing agents for alkaline earth metal ions and heavy metal ionsused in a wide variety of industrial areas with their ranges ofrequirements and problems which in some cases differ greatly from oneanother are still normally systems which have been known and used for along time such as polyphosphates, nitrilotriacetic acid orethylenediaminetetraacetic acid. However, these agents show certaindisadvantages, and the main weak points are, in particular, theircalcium- and manganese-binding capacities which are still in need ofimprovement, their as yet non-optimal stabilizing action in bleachingbaths and bleaching systems, and their biodegradability and ability tobe eliminated, which are usually inadequate.

It was therefore an object of the present invention to providecomplexing agents which no longer have the disadvantages of the priorart.

Accordingly, the use of glycine-N,N-diacetic acid derivatives of thegeneral formula I ##STR1## in which

R is C₁ - to C₃₀ -alkyl or C₂ - to C₃₀ -alkenyl, which can additionallycarry as substituents up to 5 hydroxyl groups, formyl groups, C₁ - to C₄-alkoxy groups, phenoxy groups or C₁ - to C₄ -alkoxycarbonyl groups andbe interrupted by up to 5 non-adjacent oxygen atoms, alkoxylate groupsof the formula --(CH₂)_(k) --(A¹ O)_(m) --(A² O)_(n) --Y, in which A¹and A² are, independently of one another, 1,2-alkylene groups with 2 to4 carbon atoms, Y is hydrogen, C₁ - to C₁₂ -alkyl, phenyl or C₁ - to C₄-alkoxycarbonyl, and k is the number 1, 2 or 3, and m and n are eachnumbers from 0 to 50, where the total of m+n must be at least 4,phenylalkyl groups with 1 to 20 carbon atoms in the alkyl, a five- orsix-membered unsaturated or saturated heterocyclic ring with up to threeheteroatoms from the group consisting of nitrogen, oxygen and sulfur,which can additionally be benzo-fused, carrying C₁ - to C₂₀ -alkylgroups, where all the phenyl nuclei and heterocyclic rings mentioned inthe meanings of R can additionally also carry as substituents up tothree C₁ - to C₄ -alkyl groups, hydroxyl groups, carboxyl groups, sulfogroups or C₁ - to C₄ -alkoxycarbonyl groups, or a radical of the formula##STR2## where A is a C₁ - to C₁₂ -alkylene bridge, preferably a C₂ - toC₁₂ -alkylene bridge, or a chemical bond, and

M is hydrogen, alkali metal, alkaline earth metal-, ammonium orsubstituted ammonium in the appropriate stoichiometric amounts,

as complexing agents for alkaline earth metal ions and heavy metal ionswith the exception of α-alanine-N,N-diacetic acid as textile detergentbuilders in powder detergent formulations and as calcium sequestrants inoral hygiene products has been found.

In a preferred embodiment, the compounds I used are those in which R isC₁ - to C₂₀ -alkyl, C₂ - to C₂₀ -alkenyl or a radical of the formula##STR3##

In a particularly preferred embodiment, the compound I used areα-alanine-N,N-diacetic acid (R=CH₃) and its alkali metal, ammonium andsubstituted ammonium salts.

Particularly suitable salts of this type are the sodium, potassium andammonium salts, in particular the trisodium, tripotassium andtriammonium salt, and organic triamine salts with a tertiary nitrogenatom.

Particularly suitable bases underlying the organic amine salts aretertiary amines such as trialkylamines with 1 to 4 carbon atoms in thealkyl, such as trimethyl- and triethylamine, and trialkanolamines with 2or 3 carbon atoms in the alkanol residue, preferably triethanolamine,tri-n-propanolamine or triisopropanolamine.

The alkaline earth metal salts which are particularly used are thecalcium and magnesium salts.

Besides methyl, particularly suitable as straight-chain or branchedalk(en)yl radicals for the radical R are C₂ - to C₁₇ -alkyl and-alkenyl, and of these in particular straight-chain radicals derivedfrom saturated or unsaturated fatty acids. Examples of specific Rradicals are: ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl,sec-butyl, tert-butyl, n-pentyl, iso-pentyl, tert-pentyl, neopentyl,n-hexyl, n-heptyl, 3-heptyl (derived from 2-ethylhexanoic acid),n-octyl, iso-octyl (derived from iso-nonanoic acid), n-nonyl, n-decyl,n-undecyl, n-dodecyl, iso-dodecyl (derived from ios-tridecanoic acid),n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl,n-octadecyl, n-nonadecyl, n-eicosyl and n-heptadecenyl (derived fromoleic acid). Mixtures may also occur for R, in particular those derivedfrom naturally occurring fatty acids and from synthetically producedindustrial acids, for example by the oxo synthesis.

C₁ - to C₁₂ -Alkylene bridges A used are, in particular, polymethylenegroups of the formula --(CH₂)_(k) --, in which k is a number from 2 to12, in particular from 2 to 8, i.e. 1,2-ethylene, 1,3-propylene,1,4-butylene, pentamethylene, hexamethylene, heptamethylene,octamethylene, nonamethylene, decamethylene, undecamethylene anddodecamethylene. Hexamethylene, octamethylene, 1,2-ethylene and1,4-butylene are particularly preferred in this connection. However, itis also possible for branched C₁ - to C₁₂ -alkylene groups to occurbesides, e.g. --CH₂ CH(CH₃)CH₂ --, CH₂ C(CH₃)₂ CH₂ --,--CH₂ CH(C₂ H₅)--or --CH₂ CH(CH₃)--.

The C₁ - to C₃₀ -alkyl and C₂ - to C₃₀ -alkenyl groups can carry up to5, in particular up to 3, additional substituents of the said type andbe interrupted by up to 5, in particular up to 3, non-adjacent oxygenatoms. Examples of such substituted alk(en)yl groups are --CH₂ OH, --CH₂CH₂ OH, --CH₂ CH₂ --O--CH₃, --CH₂ CH₂ --O--CH₂ CH₂ O--CH₃, --CH₂--O--CH₂ CH₃, --CH₂ --O--CH₂ CH₂ --OH, --CH₂ --CHO, --CH₂ OPh, --CH₂--COOCH₃ or --CH₂ CH₂ --COOCH₃.

Particularly suitable alkoxylate groups are those in which m and n areeach numbers from 0 to 30, in particular from 0 to 15. A¹ and A² aregroups derived from butylene oxide and, in particular, from propyleneoxide and from ethylene oxide. Of particular interest are pureethoxylates and pure propoxylates, but ethylene oxide/propylene oxideblock structures can also occur.

Suitable five- or six-membered unsaturated or saturated heterocyclicrings with up to three heteroatoms from the group consisting ofnitrogen, oxygen and sulfur, which can additionally be benzo-fused andsubstituted by the specified radicals, are:

tetrahydrofuran, furan, tetrahydrothiophene, thiophene,2,5-dimethylthiophene, pyrrolidine, pyrroline, pyrrole, isoxazole,oxazole, thiazole, pyrazole, imidazoline, imidazole, 1,2,3-triazolidine,1,2,3- and 1,2,4-triazole, 1,2,3-, 1,2,4- and 1,2,5-oxadiazole,tetrahydropyran, dihydropyran, 2H- and 4H-pyran, piperidine, 1,3- and1,4-dioxane, morpholine, pyrazane, pyridine, α-, β- and γ-picoline, α-and γ-piperidone, pyrimidine, pyridazine, pyrazine, 1,2,5-oxathiazine,1,3,5-, 1,2,3- and 1,2,4-triazine, benzofuran, thionaphthene, indoline,indole, isoindoline, benzoxazole, indazole, benzimidazole, chroman,isochroman, 2H- and 4H-chromene, quinoline, isoquinoline,1,2,3,4-tetrahydroisoquinoline, cinnoline, quinazoline, quinoxaline,phthalazine and benzo-1,2,3-triazine.

N-H groups in the said heterocyclic rings should where possible bepresent in derivatized form, for example as N-alkyl group.

In the case of substitution on the phenyl nuclei or the heterocyclicrings there are preferably two (identical or different) or, inparticular, a single substituent.

Examples of optionally substituted phenylalkyl groups and heterocylicrings carrying alkyl groups for R are

benzyl, 2-phenylethyl, 3-phenylpropyl, 4-phenylbutyl, o-, m- orp-hydroxylbenzyl, o-, m- or p-carboxylbenzyl, o-, m- or p-sulfobenzyl,o-, m- or p-methoxy or -ethoxycarbonylbenzyl, 2-furylmethyl,N-methylpiperidin-4-ylmethyl or 2-, 3- or 4-pyridinylmethyl.

In the case of substitution on phenyl nuclei and on heterocyclic rings,preferably groups which confer solubility in water, such as hydroxylgroups, carboxyl groups or sulfo groups, occur.

Examples of the said C₁ - to C₄ -, C₁ - to C₁₂ - and C₁ - to C₂₀ -alkylgroups are also to be regarded as the corresponding radicals listedabove for R.

A preferred use is in industrial cleaner formulations for hard surfacesmade of metal, plastic, paint or glass.

Industrial cleaner formulations were sought for cleaning hard surfaces,in particular with improved properties in the removal of dirt. It isadditionally desirable, to reduce waste water pollution, entirely todispense with the organic solvents which are normally also used in suchcases.

Particularly suitable areas of use are industrial cleaner formulationscontaining glycine-N,N-diacetic acid derivatives I or their salts are:

alkaline rust removers

alkaline dip degreasers

all-purpose cleaners

car-wash compositions for brush and high-pressure washes

steam jet cleaners

electrolytic degreasers, especially for steel

electrolytic rust removers

electrolytic descalers

highly alkaline cleaners

high-pressure cleaners

chain lubricants for the conveying belts of bottle filling and cleaningsystems

passivating agents for steel

spray cleaners

aqueous cold cleaners

As a rule, these cleaner formulations contain 0.1 to 30% by weight ofglycine-N,N-diacetic acid derivatives I or their salts.

Formulations customary for individual areas of use are known inprinciple to the skilled worker. As a rule, besides the complexingagents, such formulations contain 1 to 35% by weight of surfactantswhich are anionic or, preferably, nonionic in nature and which arefoaming or low-foam depending on the purposes of use, and, if required,as further aids further complexing agents, builders, foam suppressants,emulsifiers, corrosion inhibitors, reducing agents, solubilizers,dispersants and preservatives in the concentrations customary for thispurpose. It is also possible for other components with a specific actionto be included, depending on the purpose of use. It is substantiallypossible to dispense with organic solvents in the formulationsdescribed.

Suggested formulations for industrial cleaning formulations of thesetypes are to be found, for example, in the technical information"Technische Reinigungsmittel" TI/ES 1167d of January 1991 of BASFAktiengesellschaft; the prior art complexing agents indicated thereinare to be replaced by glycine-N,N-diacetic acid derivatives I or theirsalts.

Another preferred use of glycine-N,N-diacetic acid derivatives I andtheir salts is in alkaline cleaner formulations for the beverage andfoodstuff industries, in particular for bottle cleaning in the beverageindustry and equipment cleaning in dairies, in breweries, in thecanning, the baked goods, the sugar, the fat-processing and themeat-processing industries.

Formulations in particular with improved properties in removing dirthave been sought for cleaning containers and equipment in the beverageand foodstuffs industries. It is additionally desirable, in order toreduce waste water pollution, entirely to dispense with organic solventsin such formulations.

The present alkaline cleaner formulations have, as a rule, pH valuesfrom 8 to 14, preferably from 9 to 13, in particular from 10 to 12.

A preferred area of use of the described cleaner formulations is bottlecleaning in the beverage industry, in particular with automaticbottle-washing machines with throughputs of up to, normally, 30,000 to70,000 bottles per hour. The dirty bottles contained, for example, beer,milk, soft drinks, fruit juices, unfermented wine or mineral water.

Another preferred area of use of the described cleaner formulations isthe cleaning of equipment in dairies. They can be used with anadvantageous effect in the cleaning of butter churns and workers, inwhich case what mainly matters is the removal of fat. Cleanerscontaining glycine-N,N-diacetic acid derivatives I or their salts areoutstandingly suitable, however, in particular where it is needed toremove residues or deposits of calcium phosphate, other calcium salts,usually of organic acids, and casein, ("milk stone"), that is to say,for example, in milk plate heaters, disk packs for milk centrifuges orstorage and transport tanks for milk.

Another preferred area of use of the described cleaner formulations isthe cleaning of equipment in breweries. In this case, the need is, inparticular, to remove residues or deposits of calcium oxalate, hopresins and protein compounds ("beer stone"), for example fromfermentation tanks, storage tanks or beer pipes.

Another preferred area of use of the described cleaner formulations isthe cleaning of equipment in the canning industry. When heating thetinplate cans which have been filled with foodstuffs and closed,normally in an autoclave, or in the final cleaning of cans, eg. in acontinuous spray machine, it is necessary also to use cleaners whichwash off the residues of the filling material without attacking thetinplate or its coating. In addition, the cleaner should prevent scaledeposits settling on the cans or in the equipment.

Another preferred area of use of the described cleaner formulations isthe cleaning of equipment in the baked goods industry, in particular thecleaning of baked and paste goods dies which are contaminated withburnt-on baking fat and dough residues. The cleaning normally takesplace by boiling with the alkaline cleaning solutions or by washing incontinuous spray systems.

Another preferred area of use of the described cleaner formulations isthe cleaning of equipment in the sugar industry. Residues orcontaminations containing calcium salts result in the production ofsucrose from sugar beets or sugar cane, and the described formulationscontain glycine-N,N-diacetic acid derivatives I or their salts areoutstandingly suitable for removing them.

Another preferred area of use of the described cleaner formulations isthe cleaning of equipment in the fat-processing industry which producesfrom fats of animal or vegetable origin in particular lard, tallow,edible oils or by catalytic hydrogenation hardened fats or fatty oils,eg. margarine. Products of this type represent, besides their importancein the foodstuffs sector, also important raw materials for producingproducts for textile finishing, paints, leather care compositions,cosmetic products, candles, soaps, surfactants, lubricants,plasticizers, cement and asphalt additives and plastics.

Another preferred area of use of the described cleaner formulations isthe cleaning of equipment in the meat-processing industry. In this caseit is necessary in particular to use cleaners which prevent scale, eg.in so-called steam jet cleaning equipment, in which a hot steam/liquidmixture impinges on the apparatus and equipment to be cleaned.

The described alkaline cleaner formulations containingglycine-N,N-diacetic acid derivatives I or their salts can be usedsubstantially free of organic solvents. Possible environmental pollutionis substantially precluded in this way.

An aqueous cleaner formulation customary for the listed areas of use inthe beverage and foodstuffs industries contains

(i) 0.05 to 30% by weight, preferably 0.1 to 25% by weight, inparticular 0.5 to 15% by weight, of glycine-N,N-diacetic acidderivatives I or alkali metal, ammonium or substituted ammonium saltsthereof,

(ii) 2 to 50% by weight, preferably 5 to 40% by weight, in particular 8to 25% by weight, of alkali metal hydroxide, carbonate, silicate or amixture thereof and

(iii) 1 to 30% by weight, preferably 2 to 25% by weight, in particular 3to 20% by weight, of surfactants.

Suitable in this connection as component (ii) are, in particular, sodiumand potassium hydroxides, but also sodium and potassium carbonates; itis also possible to use mixtures of said alkalies.

It is possible to use as surfactants (iii) all conventional anionic ornonionic surfactants or mixtures thereof, but alkyl sulfates,alkylsulfonates, fatty alcohol alkoxylates, oxo alcohol alkoxylates,alkyl polyglucosides and fatty amine alkoxylates are particularlysuitable.

This composition represents a basic formulation for all stated areas ofapplication. Specific composition differing from one another within thisbasic formulation are to be explained by the various types of foodstuffand beverage contaminations, the different amounts of alkaline earthmetal ions in these residues and deposits and by the differences in thesensitivity of the materials in the containers and equipment to becleaned in the various areas of application. It is also worth mentioningin this connection that the described alkaline cleaner formulationswhich contain glycine-N,N-diacetic acid derivatives I or their salts asa rule cause no corrosion, even on sensitive equipment materials.

The basic formulation of components (i) to (iii) described above canalso contain conventional aids in the concentration customary in suchcases, for example disinfectants to achieve the desired degree ofbacteriological cleanliness, wetting agents, solubilizers, growthinhibitors or preservatives.

Another preferred use of glcyine-N,N-diacetic acid derivatives I andtheir salts is in dishwashing composition formulations, in particular inphosphate-free compositions for mechanical dishwashing in dishwashingmachines in the household or in commercial operations, eg. largekitchens or restaurants.

Another preferred use of glycine-N,N-diacetic acid derivatives I andtheir salts is in bleaching baths in the paper industry. In this case,complexing agents are required in reductive bleaching, eg. with sodiumdithionite, or in oxidative bleaching, eg. with hydrogen peroxide, inorder to increase the efficiency of the bleaching process, ie. thedegree of whiteness of the wooden ship. The complexing agents are thusused to eliminate heavy metal cations, mainly of iron, copper and, inparticular, manganese, which also interfere with resin sizing with alumand sodium resinate owing to the formation of insoluble salts. Thedeposition of iron onto the paper leads to "hot spots" at whichoxidative catalytic decomposition of the cellulose starts.

A typical formulation of an aqueous reductive bleaching bath of thistype in the paper industry for ground wood pulp (for example 4% stockconsistency) contains 0.05 to 0.1% by weight of complexing agent I andabout 1% by weight of sodium dithionite, in each case based on theground wood pulp. The bath temperature is about 60, the bleaching timeis normally 1 hour and the pH is about 5.8.

A typical formulation of an aqueous oxidative bleaching bath of thistype in the paper industry for ground wood pulp (for example 20% stockconsistency) contains 0.05 to 0.15% by weight of complexing agent I,about 2% by weight of waterglass, about 0.75% by weight of NaOH andabout 1% by weight of H₂ O₂, in each case based on the ground wood pulp.The bath temperature is about 50° C. and bleaching time is normally 2hours.

Another preferred use of glycine-N,N-diacetic acid derivatives I andtheir salts is in photographic bleaching and bleaching-fixing baths.These compounds can be used in such baths in the photographic industrywhich are made up with hard water in order to prevent the precipitationof sparingly soluble calcium and magnesium salts. The precipitates leadto gray fogs on films and pictures and deposits in the tanks, which canthus be advantageously avoided. They can advantageously be used asiron(IIII) complexing agent solutions in bleaching-fixing baths wherethey can replace the hexacyanoferrate solutions which are objectionablefor ecological reasons.

A typical aqueous photographic bleaching or bleaching-fixing bathformulation of this type looks as follows:

    ______________________________________                                        Iron(III) complex with complexing                                                                  0.04    to 0.4 mol/l                                     agent I                                                                       Free complexing agent I      to 1.3 mol/l                                     Sodium thiosulfate   0.2     to 2.0 mol/l                                     Sodium sulfite       0.2     to 0.3 mol/l                                     ______________________________________                                    

The pH of such a bath is normally 4 to 8.

Another preferred use of glycine-N,N-diacetic acid derivatives I andtheir salts is in pretreatment and bleaching baths in the textileindustry. Pretreatment baths mean, in particular, desizing baths andalkaline pretreatment or mercerizing baths. These compounds can thus beused in the textile industry to remove traces of heavy metals during theproduction process for natural and synthetic fibers such as cotton, woolor polyester. In this way, many impairments such as dirt spots andstreaks on the textiles, loss of brightness, poor wettability, unleveldyeings and color faults are prevented.

A typical aqueous pretreatment bath of this type for textile manufacturecontains:

    ______________________________________                                        0.1 to 10% by weight of the complexing agent I,                               0.5 to 20% by weight of conventional wetting agents or                                   emulsifiers,                                                       0 to 10%   by weight of a reducing agent such as sodium                                  dithionite,                                                        0 to 5%    by weight of a buffer mixture to adjust a pH                                  between 5 and 10                                                   ______________________________________                                    

and further conventional aids such as preservatives or desizing agents,eg. enzymes such as amylase.

Another preferred use of glycine-N,N-diacetic acid derivatives I andtheir salts is in electroplating baths for sequestering contaminatingheavy metal cations. In this case, they act as substitute for the highlytoxic cyanides.

A typical composition of an aqueous electroplating bath of this type forthe deposition of, for example, copper, nickel, zinc or gold which maybe mentioned is the following copper bath:

    ______________________________________                                        about 10 g/l copper(II) sulfate pentahydrate                                  10 to 12 g/l formaldehyde                                                     12 to 15 g/l complexing agent I                                               1 to 2 g/l   of a C.sub.13 /C.sub.15 oxo alcohol which has been                            reacted with 12 mol of ethylene oxide and                                     6 mol of propylene oxide, as wetting agent                       ______________________________________                                    

This bath is normally adjusted to pH 13 with sodium hydroxide solution;it may also contain conventional stabilizers such as amines or sodiumcyanide.

As another preferred use, copper, iron, manganese and zinc complexes ofthe compounds I are used in plant feeding to eliminate heavy metaldeficits. The heavy metals are given in this way as chelates in order toprevent precipitation as biologically inactive insoluble salts.

Glycine-N,N-diacetic acid derivatives I and their salts can in generalbe used in an advantageous manner wherever precipitates of calcium,magnesium and heavy metal salts interfere in industrial processes andare to be prevented, for example to prevent deposits and encrustationsin boilers, pipelines, on spray nozzles or generally on smooth surfaces.

They can be used to stabilize phosphates in alkaline degreasing bathsand prevent the precipitation of lime soaps and, in this way, preventthe "tarnishing" of non-ferrous surfaces and extend the useful lives ofalkaline cleaner baths.

Cooling water treatment with the compounds I prevents deposits orredissolves those already present. One advantage is the generalapplicability in an alkaline medium and thus the elimination ofcorrosion problems.

They can be used to prepare the redox catalyst used in thepolymerization of rubber. They additionally prevent the precipitation ofiron hydroxide in the alkaline polymerization medium.

The compounds I can be used as complexing agent or as builder in powderdetergent formulations for textile washing. A use of this type asbuilder has already been disclosed for α-alanine-N,N-diacetic acid.Besides conventional formulations (bulk density about 450 g/l), in thisconnection compact and ultra-compact detergents (bulk density ≳700 g/l)are becoming increasingly important. As is well known, compact detergentformulations have a higher content of detergent substance (surfactants),builders (eg. zeolites), bleaches and polymers than conventional powderdetergents. The compounds I are normally effective in such compactdetergent formulations in amounts of from 0.1 to 25% by weight, inparticular 1 to 15% by weight.

In liquid detergent formulations for textile washing, the compounds Ican be used as complexing agents in an amount of from 0.05 to 20% byweight based on the total weight of the detergent formulation.

In liquid detergent formulations, the compounds I can furthermore alsobe used as preservatives, expediently in an amount of from 0.05 to 1% byweight based on the total weight of the detergent formulation.

In soaps, they prevent metal-catalyzed oxidative decompositions.

Examples of further suitable applications are applications inpharmaceuticals, cosmetics and foodstuffs in order, for example, toprevent the metal-catalyzed oxidation of olefinic double bonds and thusthe products becoming rancid.

Other areas of application of the compounds I are in flue gas scrubbing,in particular to remove NO_(x) from flue gases, in H₂ S oxidation, inmetal extraction and the application as catalysts for organic syntheses,eg. atmospheric oxidation of paraffins or hydroformulation of olefins toalcohols.

An advantageous effect of the glycine-N,N-diacetic acid derivatives I ortheir salts is in bleach stabilization, for example in the bleaching oftextiles, cellulose or paper. Traces of heavy metals such as iron,copper and manganese occur in the components of the bleaching bathitself, in the water and in the material to be bleached and catalyze thedecomposition of the bleach. The complexing agents I bind these metalions and prevent unwanted decomposition of the bleaching system duringstorage and on use. In this way, the efficiency of the bleaching systemis increased, and damage to the material to be bleached is diminished.

Another advantageous effect of the glycine-N,N-diacetic acid derivativesI or their salts is in the strong bleach-activating effect of complexesof compounds I with manganese, in particular manganese of oxidationstate II and IV. Complexes of this type can be used as substitute forconventional bleach activators in textile detergent formulations asbleach catalysts in amounts in the ppm range.

Glycine-N,N-diacetic acid derivatives I and their salts are suitable forthe described purposes of use in particular because they representexceptionally efficient complexing agents for alkaline earth metal ionsand for heavy metal ions, in particular for calcium and manganese. Theircalcium- and their manganese-binding capacities are exceptionally high.

Further advantages are their very low toxicity potential and their goodbiodegradability. Thus, α-alanine-N,N-diacetic acid shows abiodegradability of >90% (28-day value) in the Zahn-Wellens test understandard conditions, whereas, for example, ethylenediaminetetraaceticacid yields a value of <10% under the same conditions.

In association with their good biodegradability, it is also veryadvantageous that the cleaner formulations containing the compounds Ican mostly be used substantially free of organic solvents. Thisprecludes possible environmental pollution even more substantially.

The present invention also relates to a process for preparingglycine-N,N-diacetic acid derivatives I and their alkali metal, alkalineearth metal, ammonium and substituted ammonium salts, which comprisesreacting

(A) appropriate 2-substituted glycines or 2-substituted glycinonitrilesor doubled glycines of the formula ##STR4## or doubled glycinonitrilesof the formula ##STR5## with formaldehyde and hydrogen cyanide or alkalimetal cyanide or

(B) iminodiacetic acid or iminodiacetonitrile with appropriatemonoaldehydes or dialdehydes of the formula OHC--A--CHO and hydrogencyanide or alkali metal cyanide

and subsequently hydrolyzing nitrile groups which are still present tocarboxyl group.

The two specified embodiments A and B represent examples of the"Strecker synthesis" in which, in general, aldehydes are reacted withammonia or amines and hydrocyanic acid ("acidic" variant) or cyanides("alikaline" variant) to give amino acids or derivatives thereof.

The "alkaline" variant of the Strecker synthesis is described in generalform, for example, in U.S. Pat. No. 3,733,355 (4). However, the examplescited therein show that a high proportion of byproducts, especially ofunwanted glycolic acid, always occurs; this can be concluded from theconversions of only a maximum of about 89%.

The "acidic" variant of the Strecker synthesis is disclosed, forexample, in DE-A 20 27 972 (5). The preparation ofcarboxymethyliminodiacetonitrile starting from glycine, formaldehyde andhydrocyanic acid in an acidic medium is described therein. It isrecommended in this case to add additional acid in order to keep the pHin the range below 7.

It was also an object of the present invention to provide a moreefficient and more economic process for preparing glycine-N,N-diaceticacid derivatives I, which, in particular, suppresses the formation ofunwanted byproducts and is able to dispense with additional auxiliaries,for example for pH control.

The process defined above has accordingly been found.

The variants which make use of hydrogen cyanide ("acidic" variant) haveproven particularly advantageous. It is expedient to use anhydroushydrogen cyanide which is normally handled in this form on theindustrial scale. In this connection, very particularly advantageousreactions are those starting from 2-substituted glycines or doubledglycines of the formula ##STR6## or from iminodiacetonitrile.

The reaction according to A or B is preferably carried out in water butalso in an organic solvent or in mixtures thereof. Organic solventswhich are preferably used are those which are partly or completelymiscible with water, eg. methanol, ethanol, n-propanol, iso-propanol,tert-butanol, dioxane or tetrahydrofuran. It is also possible to usesolubilizers.

In embodiment A it is expedient to use per mole of amino compound 2 to2.6 mol of formaldehyde, preferably in the form of its aqueousapproximately 30% by weight solution, or 2 to 2.6 mol of aldehyde, inanhydrous form or as aqueous solution, and 2 to 2.3 mol of hydrogencyanide or alkali metal cyanide, for example sodium or potassiumcyanide. The reaction is normally carried out at temperatures from 0° to120° C., in particular 15° to 80° C., in the case of anhydrous hydrogencyanide, and at 40° to 110° C., in particular 70° to 100° C., in thecase of alkali metal cyanides. A suitable pH range for the reaction withanhydrous hydrogen cyanide when mineral acids such as sulfuric,hydrochloric or orthophosphoric acid are also used in embodiment B is,as a rule, from 0 to 11, in particular from 1 to 9, and the reactionwith alkali metal cyanides is normally carried out at pH 10 to 14, inparticular 11 to 13.

This reaction is followed by a hydrolysis of nitrile groups which arestill present to carboxyl groups, which is carried out in a manner knownper se in aqueous reaction medium in the presence of bases such assodium or potassium hydroxide solution or of acids such as sulfuric orhydrochloric acid at temperatures from 20° to 110° C., in particular 40°to 100° C.

The glycine and glycinonitrile derivatives used as starting aminocompounds can be used both as racemates and as enantiomerically pure Dor L compounds.

According to the reaction conditions, the glycine-N,N-diacetic acidderivatives I are obtained as free carboxylic acid or, for example, asalkali metal salt. The required salts can be prepared without difficultyfrom the free acid by neutralization with the appropriate bases, forexample amine bases.

The glycine-N,N-diacetic acid derivatives I and their salts can beisolated in pure form from their solutions without difficulty. Suitablefor this purpose are, in particular, spray or freeze drying,crystallization and precipitation. It may be advantageous for thesolution produced in the preparation to be supplied directly forindustrial use.

The present invention also relates to the glycine-N,N-diacetonitrilesand glycinonitrile-N,N-diacetonitriles which have not yet been disclosedin the literature and are substituted by the radical R in position 2, inwhich R is C₁ - to C₃₀ -alkyl or C₂ - to C₃₀ -alkenyl which canadditionally carry as substituents up to 5 hydroxyl groups, formylgroups, C₁ - to C₄ -alkoxy groups, phenoxy groups or C₁ - to C₄-alkoxycarbonyl groups and be interrupted by up to 5 non-adjacent oxygenatoms, alkoxylate groups of the formula --(CH₂)_(k) --O--(A¹ O)_(m)--(A² O)_(n) --Y, in which A¹ and A² are, independently of one another,1,2-alkylene groups with 2 to 4 carbon atoms, Y is hydrogen, C₁ - to C₁₂-alkyl, phenyl or C₁ - to C₄ -alkoxycarbonyl, and k is the number 1, 2or 3, and m and n are each numbers from 0 to 50, where the total of m+nmust be at least 4, phenylalkyl groups with 1 to 20 carbon atoms in thealkyl, a five- or six-membered unsaturated or saturated heterocyclicring with up to three heteroatoms from the group consisting of nitrogen,oxygen and sulfur, which can additionally be benzo-fused, carrying C₁ -to C₂₀ -alkyl groups, where all phenyl nuclei and heterocyclic ringsmentioned in the meanings for R can additionally carry as substituentsup to three C₁ - to C₄ -alkyl groups, hydroxyl groups, carboxyl groups,sulfo groups or C₁ - to C₄ -alkoxycarbonyl groups, for example thecompounds α-alanine-N,N-diacetonitrile andα-alaninonitrile-N,N-diacetonitrile, and doubledglycine-N,N-diacetonitriles and doubledglycinonitrile-N,N-diacetonitriles of the formula ##STR7## where X is acarboxylic acid or a nitrile functionality, as intermediates for thepreparation of glycine-N,N-diacetic acid derivatives I and their salts.These compounds arise as intermediates in the reaction of said glycineand glycinonitrile derivatives for formaldehyde and hydrogen cyanide orof iminodiacetonitrile with the appropriate mono- or dialdehydes andhydrogen cyanide.

In the process according to the invention it is possible with the"acidic" variant of embodiment A with glycines substituted in position 2or doubled glycines of the formula ##STR8## as starting material todispense with additional acid because, astonishingly, the acidity of thecarboxyl group which is present is sufficient to carry out the reaction.

The reaction product is generally obtained in high yield in sufficientlypure form. The content of byproducts is low. Further advantages of thepreparation process according to the invention are the salt-freeprocedure and the easily available starting materials.

The present invention also relates to the glycine-N,N-diacetic acidderivatives of the general formula Ia ##STR9## which have not yet beendescribed in the literature, and in which

R' is C₄ -C₃₀ -alkyl, in particular C₅ -C₃₀ -alkyl, or C₂ -C₃₀ -alkenyl,which can additionally carry as substituents up to 5 hydroxyl groups,formyl groups, C₁ - to C₄ -alkoxy groups, phenoxy groups or C₁ - to C₄-alkoxycarbonyl groups and be interrupted by up to 5 non-adjacent oxygenatoms, alkoxylate groups of the formula --(CH₂)_(k) --O--(A¹ O)_(m)--(A² O)_(n) --Y, in which A¹ and A² are, independently of one another,1,2-alkylene groups with 2 to 4 carbon atoms, Y is hydrogen, C₁ - to C₁₂-alkyl, phenyl or C₁ - to C₄ -alkoxycarbonyl, and k is the number 1, 2or 3, and m and n are each numbers from 0 to 50, where the total of m+nmust be at least 4, phenylalkyl groups with 1 to 20 carbon atoms in thealkyl, a five- or six-membered unsaturated or saturated heterocyclicring with up to three heteroatoms from the group consisting of nitrogen,oxygen and sulfur, which can additionally be benzo-fused, carrying C₁ -to C₂₀ -alkyl groups, where all phenyl nuclei and heterocyclic ringsmentioned in the meanings for R can additionally carry as substituentsup to three C₁ - to C₄ -alkyl groups, hydroxyl groups, carboxyl groups,sulfo groups or C₁ - to C₄ -alkoxycarbonyl groups, or a radical of theformula ##STR10## where A' is a C₁ - to C₁₂ -alkylene bridge, and

M is hydrogen, alkali metal, alkaline earth metal, ammonium orsubstituted ammonium in the appropriate stoichiometric amounts.

The compounds I with R=C₁ - to C₃ -alkyl have already been disclosed inthe reference Chem. zvesti 28(3), 332-335 (1974).

PREPARATION EXAMPLES Example 1

Preparation of α-D,L-alanine-N,N-diacetic trisodium salt fromiminodiacetonitrile

14 g of sulfuric acid (100% by weight), 27 g of anhydrous hydrocyanicacid and 44 g of acetaldehyde (100% by weight) were successively addedto a suspension of 95 g of iminodiacetonitrile (100% by weight) in 500ml of water at 35° to 50° C. The mixture was stirred until no furtherchange was found on titration of the hydrocyanic acid content. Aftercooling to 10° C, the precipitate was filtered off and dried. 123.4 g ofα-D,L-alaninonitrile-N,N-diacetonitrile (corresponding to 83% of theory)of melting point 82° C. resulted.

The resulting α-D,L-alaninonitrile-N,N-diacetonitrile was introduced at50° C. into 440 g of 25% by weight aqueous sodium hydroxide solution,and the mixture was then stirred at this temperature for a further 2hours. It was then heated at 95° C. for 10 hours. Towards the end of thereaction, the reaction mixture was diluted with water. This resulted in610 g of an aqueous solution of α-D,L-alanine-N,N-diacetic acidtrisodium salt with an iron-binding capacity of 1.285 mmol/g(corresponding to 94% of theory based onα-D,L-alaninonitrile-N,N-diacetonitrile used).

Example 2

Preparation of α-D,L-alanine-N,N-diacetic acid trisodium salt fromα-D,L-alanine

105 g of formaldehyde (30% by weight) and 31.7 g of hydrocyanic acid(89.5% by weight) were added simultaneously to a suspension of 44 g ofD,L-alanine (>99% by weight) in 200 g of water at 30° C. The mixture wasthen stirred at 30° C. for 3 hours. The decrease in hydrocyanic acidcorresponded to a conversion of >97% of theory.

The aqueous solution of α-D,L-alanine-N,N-diacetonitrile obtained inthis way was added dropwise to 132 g of 50% by weight sodium hydroxidesolution at 30° C. After stirring at 30° C. for 8 hours, the temperaturewas raised to 95° to 102° C. After a further 4 hours, the reaction wasvirtually complete. 352.5 g of a solution which, according to itsiron-binding capacity, contained 37.4% by weight ofα-D,L-alanine-N,N-diacetic acid trisodium salt were obtained(corresponding to a yield of 97.4% of theory over the two stages).

Example 3

L-Tyrosine-N,N-diacetic acid trisodium salt from L-tyrosine

45.8 g of tyrosine were suspended in 200 ml of water, and 7.5 g of HCN(90% by weight) and 25 g of formaldehyde (30% by weight) in aqueoussolution were added. After 2.5 h at 40° C., the conversion ofhydrocyanic acid was a maximum, and a further 12.0 g of HCN (90% byweight) and 40.0 g of formaldehyde (30% by weight) in aqueous solutionwere added at pH 1. After a further 5 h at 35° C. and 4 h at 80° C., asolution of L-tyrosine-N,N-diacetonitrile was obtained in 94% yield oftheory.

This solution was added dropwise to 130 g of 50% by weight aqueoussodium hydroxide solution at 40° C. After 2 h at 60° C. and 2 h at 95°C., 385 g of a solution of L-tyrosine-N,N-diacetic acid trisodium saltwith an iron-binding capacity of 0.543 mmol/g (corresponding to 89% ofthe theoretical yield) were obtained.

Example 4

D,L-Ethylglycine-N,N-diacetic acid trisodium salt fromiminodiacetonitrile

41 g of sulfuric acid (96% by weight), 180 g of hydrogen cyanide (99% byweight) and 385 g of propionaldehyde (99.5% by weight) were successivelyadded dropwise to a suspension of 570 g of iminodiacetonitrile in 2070 gof water, and the mixture was stirred at 35° C. until no further changein the hydrocyanic acid content was detectable by titration. Aftercooling to 10° C., 977 g (97% yield of theory) ofD,L-ethylglycinonitrile-N,N-diacetonitrile were obtained as precipitateby filtration with a purity of 96.8% by weight.

The precipitate was then introduced into 4430 g of a 17% by weightaqueous sodium hydroxide solution at 60° C. and then stirred at 60° C.for 3 h and at 95° C. for 10 h, and finally diluted with water. Thisresulted in 5275 g of a solution of D,L-ethylglycone-N,N-diacetic acidtrisodium salt with an iron-binding capacity of 0.985 mmol/g(corresponding to 89% yield of theory).

Example 5

D,L-Propylglycine-N,N-diacetic acid trisodium salt fromiminodiacetonitrile

14 g of sulfuric acid (96% by weight), 26.9 g of hydrogen cyanide(99.3%) and 79.3 g of butyraldehyde were successively added dropwise toa suspension of 95 g of iminodiacetonitrile in 550 g of water, and themixture was stirred at 35° C. for 4 h until no further change in thehydrocyanic acid content was detectable by titration. After cooling to10° C., 165 g (94% yield of theory) ofD,L-n-propylglycinonitrile-N,N-diacetonitrile were obtained by phaseseparation.

70.4 g of this oil were then introduced into 350 g of a 15% by weightaqueous sodium hydroxide solution at 40° C., and the mixture was thenstirred at 95° C. for 2 h and subsequently diluted with water. Thisresulted in 600 g of a solution of D,L-n-propylglycine-N,N-diacetic acidtrisodium salt with an iron-binding capacity of 0.573 mmol/g(corresponding to 86%.yield of theory).

Example 6

D,L-1-Methylpropylglycine-N,N-diacetic acid trisodium salt fromiminodiacetonitrile

6 g of sulfuric acid (96% by weight), 30 g of hydrogen cyanide (99.4% byweight) and 103.2 g of 2-methylbutyraldehyde were successively addeddropwise to a suspension of 95 g of iminodiacetonitrile in 350 g ofwater, and the mixture was stirred at 35° C. for 2 h and at 55° C. for25 h until no further change in the hydrocyanic acid content wasdetectable by titration. After cooling to 10° C., 167 g (88% yield oftheory) of D,L-1-methylpropylglycinonitrile-N,N-diacetonitrile wereobtained by phase separation.

143 g of this oil were then introduced into 600 g of an 18% by weightaqueous sodium hydroxide solution at 40° C. and this was then stirred at95° h for 20 h and subsequently diluted with water. This resulted in 960g of a solution of D,L-1-methylpropylglycine-N,N-diacetic acid trisodiumsalt with an iron-binding capacity of 0.619 mmol/g (corresponding to 79%yield of theory).

Example 7

D,L-2-Methylpropylglycine-N,N-diacetic acid trisodium salt fromiminodiacetonitrile

7 g of sulfuric acid (96% by weight), 30 g of hydrogen cyanide (98.3% byweight) and 103.4 g of 3-methylbutyraldehyde were successively addeddropwise to a suspension of 95 g of aminodiacetonitrile in 350 g ofwater, and the mixture was stirred at 35° C. for 2 h and at 50° C. for 3h until no further change in the hydrocyanic acid content was detectableby titration. After cooling to 10° C., 175 g (92% yield of theory) ofD,L-2-methylpropylglycinonitrile-N,N-diacetonitrile were obtained byphase separation.

The resulting oil was then introduced into 860 g of a 14% by weightaqueous sodium hydroxide solution at 40° C. and then stirred at 60° C.for 3 h and at 95° C. for 5 h. This resulted in 1070 g of a solution ofD,L-2-methylpropylglycine-N,N-diacetic acid trisodium salt with aniron-binding capacity of 0.775 mmol/g (corresponding to 90% yield oftheory).

Example 8

D,L-n-Nonylglycine-N,N-diacetic acid from iminodiacetonitrile

14 g of sulfuric acid (96% by weight), 30.2 g of hydrogen cyanide (98.4%by weight) and 172 g of n-decanal were successively added dropwise to asuspension of 95 g of iminodiacetonitrile in 500 g of water, and themixture was stirred at 60° C. for 17 h and at 80° C. for 2 h until nofurther change in the hydrocyanic acid content was detectable bytitration. After cooling to 10° C., the aqueous phase was separated offand the remaining oil was extracted by shaking twice with 500 ml ofwater, and 205 g (79% yield of theory) ofD,L-n-nonylglycinonitrile-N,N-diacetonitrile were obtained from theorganic phase.

205 g of this oil were then introduced into 600 g of an 18% by weightaqueous sodium hydroxide solution together with 600 ml of n-butanol at40° C. and the mixture was stirred at 95° C. for 30 h. The volatileswere then removed by distillation, and the residue was taken up inwater, adjusted to pH 1 with HCl, and the precipitate which formed wasisolated by filtration. This resulted in 209 g ofD,L-n-nonylglycine-N,N-diacetic acid with an iron-binding capacity of2.57 mmol/g (corresponding to 68% yield of theory).

Example 9

D,L-n-Tridecylglycine-N,N-diacetic acid from iminodiacetonitrile

14 g of sulfuric acid (96% by weight), 30.2 g of hydrogen cyanide (98.4%by weight) and 234 g of n-tetradecanal were successively added dropwiseto a suspension of 95 g of iminodiacetonitrile in 500 g of water, andthe mixture was stirred at 60° C. for 17 h and at 80° C. for 2 h untilno further change in the hydrocyanic acid content was detectable bytitration. After cooling to 10° C., the aqueous phase was separated offand the remaining oil was extracted by shaking twice with 500 ml ofwater, and 259 g (82% yield of theory) ofD,L-n-tridecylglycinonitrile-N,N-diacetonitrile were obtained from theorganic phase.

259 g of this oil were then introduced into 600 g of an 18% by weightaqueous sodium hydroxide solution together with 600 ml of n-butanol at40° C. and the mixture was stirred at 95° C. for 30 h. The volatileswere then removed by distillation, and the residue was taken up inwater, adjusted to pH 1 with HCl, and the wax-like precipitate whichformed was isolated by filtration. This resulted in 252 g ofD,L-n-tetradecylglycine-N,N-diacetic acid with an iron-binding capacityof 2.14 mmol/g (corresponding to 66% yield of theory).

Example 10

D,L-(2-Phenylethylene)glycine-N,N-diacetic acid trisodium salt fromiminodiacetonitrile

3.5 g of sulfuric acid (96% by weight), 8.0 g of hydrogen cyanide (98.3%by weight) and 35.2 g of 3-phenylpropionaldehyde were successively addeddropwise to a suspension of 23.8 g of iminodiacetonitrile in 125 g ofmethanol, and the mixture was stirred at 50° C. for 50 h, after whichtime the conversion according to the hydrocyanic acid content was 95.5%of theory.

Then 190 g of the untreated solution ofD,L-(2-phenylethylene)-glycinonitrile-N,N-diacetonitrile in methanolwere introduced into 186 g of a 19% by weight aqueous sodium hydroxidesolution at 40° C., and the mixture was stirred at 60° C. for 3 h and at95° C. for a further 22 h, with the methanol which distilled out beingreplaced by water. This resulted in 510 g of a solution ofD,L-(2-phenylethylene)glycine-N,N-diacetic acid trisodium salt with aniron-binding capacity of 0.368 mmol/g (corresponding to 75% yield oftheory). Acidification to pH 1.5, filtration of the precipitate whichformed with suction and washing with methanol at 40° C. resulted in thecorresponding free acid in a purity of 96% by weight.

Example 11

2-Furylmethyleneglycine-N,N-diacetic acid from iminodiacetonitrile

4.8 g of sulfuric acid (96% by weight), 16.5 g of hydrogen cyanide(90.2% by weight) and 52.9 g of furfural were successively addeddropwise to a suspension of 47.5 g of iminoacetonitrile in 200 g ofwater, and the mixture was stirred at 60° C. for 6 h and at 85° C. for 8h until no further change in the hydrocyanic acid content was detectableby titration. The mixture was saturated with sodium chloride andextracted three times by shaking with methyl tert-butyl ether. Thecombined organic phases were cooled to -20° C., and the precipitatewhich formed was isolated. 95 g (89% yield of theory) ofD,L-2-furylmethyleneglycinonitrile-N-N-diacetonitrile resulted.

46 g of these crystals were then introduced into 130 g of a 22% byweight aqueous sodium hydroxide solution at 40° C., and the mixture wasstirred at 40° C. for 3 h and at 95° C. for 4 h. It was subsequentlyadjusted to pH 1.5 with HCl, and the precipitate which formed wasisolated by filtration and washed with water. This resulted in 47 g ofD,L-2-furylmethyleneglycine-N,N-diacetic acid with an iron-bindingcapacity of 3.61 mmol/g (corresponding to 79% yield of theory).

Example 12

1,3-Propylenebis(D,L-glycine-N,N-diacetic acid) hexasodium salt fromiminodiacetonitrile

14 g of sulfuric acid (96% by weight), 33.1 g of hydrogen cyanide (89.8%by weight) and 220 g of glutaraldehyde (25% by weight in water) weresuccessively added dropwise to a suspension of 95 g ofiminodiacetonitrile in 410 g of water, and the mixture was stirred at35° C. for 2 h and at 70° C. for 6 h until no further change in thehydrocyanic acid content was detectable by titration (99.1% conversionof theory). After cooling to 10° C., the aqueous phase was separated offand the remaining oil was extracted by shaking twice with 500 ml ofwater, and 149 g (97% yield of theory) of1,2-propylenebis(D,L-glycinonitrile-N,N-diacetonitrile) were obtainedfrom the organic phase.

Then 149 g of this oil were introduced into 744 g of a 19% by weightaqueous sodium hydroxide solution at 30° C., and the mixture was stirredat 70° C. for 12 h and at 100° C. for 11 h. 572 g of a solution of1,3-propylenebis(D,L-glycine-N,N-diacetic acid) hexasodium salt with aniron-binding capacity of 0.829 mmol/g (corresponding to 99% of thetheoretical yield) were obtained. The product was isolated pure byadding methanol to the solution.

Technical application data and application examples

Determination of the calcium-binding capacity

Principle of the measurement

The inhibiting effect of complexing agents or dispersants on theprecipitation of calcium carbonate is determined by turbidity titration.The substance to be investigated is introduced and titrated in thepresence of sodium carbonate with calcium acetate solution. The endpointis indicated by formation of the calcium carbonate precipitate. Use of asufficient amount of sodium carbonate ensures that the measurementprovides a correct result even if the effect derives not only fromcomplexation of the calcium ions but from dispersion of calciumcarbonate. This is so because if the amounts of sodium carbonate usedare too small there is a risk that the dispersing capacity of theproduct will not be exhausted; in this case, the titration endpoint isdetermined by precipitation of the calcium salt of the compoundinvestigated.

During the titration, the change in the light transmission is followedwith the aid of a light-guide photometer. In the latter, a light beamguided via a glass fiber into the solution is reflected at a mirror, andthe intensity of the reflected light is measured.

Reagents

0.25M Ca(OAc)₂ solution

10% by weight Na₂ CO₃ solution

1N NaOH solution

1% by weight hydrochloric acid

Procedure

1 g of active substance (A.S.) in the form of the trisodium salt isdissolved in 100 ml of distilled H₂ O. Subsequently 10 ml of 10% byweight Na₂ CO₃ solution are added. Automatic titration is carried outwith 0.25M Ca(OAc)₂ solution continuously at 0.25 ml/min and at roomtemperature (RT) with a pH of 11 kept constant during the titration andat 80° C. with a pH of 10.

Calculation

Amount in mg of CaCO₃ /g of A.S.=ml of Ca(OAc)₂ solution used×25. In theautomatic titration, the 1st break point in the titration plot is theendpoint.

Furthermore, the perborate stabilization of the cleaner formulations 1and 2 of the compositions indicated below was determined

The hydrogen peroxide which is responsible for the bleaching action indetergent formulations containing sodium perborate is catalyticallydecomposed by heavy metal ions (Fe, Cu, Mn). This can be prevented bycomplexing the heavy metal ions. The peroxide-stabilizing effect of thecomplexing agents is tested via the remaining peroxide content afterstorage of a wash liquor containing heavy metals in the warm. Thehydrogen peroxide content was determined before and after the storage bytitration with potassium permanganate in acidic solution.

Two detergent formulations are used to test for perborate stabilization,the decomposition taking place on storage in the warm by adding heavymetal catalysts (2.5 ppm mixture of 2 ppm Fe³⁺, 0.25 ppm Cu²⁺, 0.25 ppmMn²⁺).

1. Phosphate-containing formulation Composition (in % by weight):

    ______________________________________                                        19.3%   sodium C.sub.12 -alkylbenzenesulfonate (50% by weight                         aqueous solution)                                                     15.4%   sodium perborate.4H.sub.2 O                                           30.8%   sodium triphosphate                                                   2.6%    copolymer of maleic acid and acrylic acid (50:50                              ratio by weight, average molecular weight 50,000)                     31.0%   sodium sulfate, anhydrous                                             0.9%    complexing agent according to the invention or com-                           parative compound                                                     ______________________________________                                    

The detergent concentration was 6.5 g/l using water of 25° Germanhardness. Storage took place at 80° C. for 2 hours.

2. Reduced phosphate formulation Composition (in % by weight):

    ______________________________________                                        15%     sodium C.sub.12 -alkylbenzenesulfonate (50% by weight                         aqueous solution)                                                     5%      adduct of 11 mol of ethylene oxide and 1 mol of tal-                          low fatty alcohol                                                     20%     sodium perborate.4H.sub.2 O                                           6%      sodium metasilicate.5H.sub.2 O                                        1.25%   magnesium silicate                                                    20%     sodium triphosphate                                                   31.75%  sodium sulfate, anhydrous                                             1%      complexing agent according to the invention or com-                           parative compound                                                     ______________________________________                                    

The detergent concentration was 8 g/l using water with 25° Germanhardness. The storage took place at 60° C. for 1 hour.

The following Table 1 shows the results of the determinations.

                  TABLE 1                                                         ______________________________________                                               Calcium carbonate dispersing                                                  capacity mg       Perborate                                                   CaCO.sub.3 /g A.S.                                                                      CaCO.sub.3 /mol A.S.                                                                      stabilization  %!                                Complex- RT      80° C.                                                                         RT    80° C.                                                                       Formulation                              ing agent                                                                              pH 11   pH 10   pH 11 pH 10 1     2                                  ______________________________________                                        α-ADA--Na.sub.3                                                                  370     330     1.00  0.89  32.4  40.8                               from Ex.                                                                      No. 2                                                                         for comparison:                                                               Penta-   215     150     0.79  0.55  --    --                                 sodium                                                                        tri-                                                                          phosphate                                                                     NTA--Na.sub.3                                                                          350     250     0.90  0.64  24.5  32.5                               EDTA--Na.sub.4                                                                         275     240     1.04  0.91  20.0  34.0                               ______________________________________                                         a-ADA--Na.sub.3 = Alanine-N,N-diacetic acid trisodium salt                    NTA--Na.sub.3 = Nitrilotriacetic acid trisodium salt                          EDTANa.sub.4 = Ethylenediaminetetraacetic acid tetrasodium salt          

Determination of the manganese-binding capacity

Method of measurement

10.0 ml of 0.005M MnSO₄ ·H₂ O solution are mixed with 50 ml of distilledwater, 10 drops of 5% by weight potassium sodium tartrate solution,about 3 ml of a buffer solution, about 30 mg of ascorbic acid and aspatula tip of indicator (1 part by weight of Eriochrome black T groundwith 400 parts by weight of NaCl) and heated to 75° C. The solution istitrated with a 0.001M solution of the complexing agent (C.A.) until thechange to blue persists.

Evaluation ##EQU1##

The following Table 2 shows the results of the determinations.

                  TABLE 2                                                         ______________________________________                                        Complexing   mg Mn.sup.2+ /g complexing                                                                    mol Mn.sup.2+ /mol                               agent        agent           complexing agent                                 ______________________________________                                        α-ADA--Na.sub.3 from                                                                 209             0.86                                             Ex. No. 2                                                                     for comparison:                                                               EDTA--Na.sub.4                                                                             192             1.02                                             ______________________________________                                    

Example 13

Highly alkaline cleaner formulation for dairies

A mixture of

40 parts by weight of 50% by weight sodium hydroxide solution,

20 parts by weight of a 30% by weight aqueous solution ofα-D,L-alanine-N,N-diacetic acid trisodium salt from Example No. 2,

4 parts by weight of a C₁₀ -oxo alcohol ethoxylate with a degree ofethoxylation of about 4,

4 parts by weight of a commercial alkylcarboxylic acid mixture assolubilizer,

7 parts by weight of sodium gluconate to break down the water hardnessand

25 parts by weight of water

was used to remove deposits of calcium phosphate, calcium oxalate,protein and ash. It was possible to remove the deposits withoutdifficulty.

Example 14

Highly alkaline cleaner formulation for breweries

A mixture of

40 parts by weight of 50% by weight potassium hydroxide solution,

20 parts by weight of a 30% by weight aqueous solution ofα-D,L-alanine-N,N-diacetic acid trisodium salt from Example No. 2,

3 parts by weight of a C₁₀ -oxo alcohol ethoxylate with a degree ofethoxylation of about 3,

3 parts by weight of a commercial alkylcarboxylic acid mixture assolubilizer and

34 parts by weight of water

was used to remove deposits of calcium oxalate, hop resins and protein.It was possible to remove the deposits without difficulty.

We claim:
 1. A process for the industrial cleaning of hard surfaces ofarticles made of metal, plastic, paint or glass, alkaline cleaning ofarticles for the beverage and foodstuff industries or for dishwashing ofarticles, comprising contacting the article with a cleaner formulationcomprising α-alanine-N-N-diacetic acid, its alkali metal, ammonium andsubstituted ammonium salts thereof.